Charge radii of the nucleon from its flavor dependent Dirac form factors

Abstract

We have determined the proton and the neutron charge radii from a global analysis of the proton and the neutron elastic form factors, after first performing a flavor decomposition of these form factors under charge symmetry in the light cone frame formulation. We then extracted the transverse mean-square radii of the flavor dependent quark distributions. In turn, these are related in a model-independent way to the proton and neutron charge radii but allow us to take into account motion effects of the recoiling nucleon for data at finite but high momentum transfer. In the proton case we find $⟨r_p⟩=0.852\pm 0.002_{(stat.)}\pm 0.009_{(syst.)}(\mathrm{fm})$, consistent with the proton charge radius obtained from muonic hydrogen spectroscopy \cite{pohl:2010,antog2013}. The current method improves on the precision of the $⟨r_p⟩$ extraction based on the form factor measurements. Furthermore, we find no discrepancy in the $⟨r_p⟩$ determination among the different electron scattering measurements, all of which, utilizing the current method of extraction, result in a value that is consistent with the smallest $⟨r_p⟩$ extraction from the electron scattering measurements \cite{Xiong:2019umf}. Concerning the neutron case, past results relied solely on the neutron-electron scattering length measurements, which suffer from an underestimation of underlying systematic uncertainties inherent to the extraction technique. Utilizing the present method we have performed the first extraction of the neutron charge radius based on nucleon form factor data, and we find $⟨r_n^2⟩=-0.122\pm 0.004_{(stat.)}\pm 0.010_{(syst.)}({\mathrm{fm}}^2)$.

References in corpus (13)

• High-precision determination of the electric and magnetic form factors of the proton
• Dispersion analysis of the nucleon form factors including meson continua
• Proton and neutron electromagnetic form factors and uncertainties
• Flavor decomposition of the elastic nucleon electromagnetic form factors
• The size of the proton - closing in on the radius puzzle
• Measurement of the proton electric to magnetic form factor ratio from \vec ^1H(\vec e, e'p)
• Theoretical Constraints and Systematic Effects in the Determination of the Proton Form Factors
• Defining the Proton Radius: a Unified Treatment
• Polarization Transfer in the 4He(e,e'p)3H Reaction at Q^2 = 0.8 and 1.3 (GeV/c)^2
• Charge Distributions of Moving Nucleons
• The Charge Form Factor of the Neutron at Low Momentum Transfer from the ${}^2\vec{\mathrm{H}}(\vec{\mathrm{e}},{\mathrm{e}}^{\prime }\mathrm{n})\mathrm{p}$ Reaction
• Extraction of the neutron charge radius from a precision calculation of the deuteron structure radius
• High-accuracy calculation of the deuteron charge and quadrupole form factors in chiral effective field theory

Cited by in corpus (11)

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• Pendellösung Interferometry Probes the Neutron Charge Radius, Lattice Dynamics, and Fifth Forces
• Low-energy nuclear physics and global neutron star properties
• Nucleon relativistic polarization and magnetization distributions
• Measured proton electromagnetic structure deviates from theoretical predictions
• Elastic Positron-Proton Scattering at Low Q${}^2$
• Note on the electromagnetic radius of proton
• The Proton Electromagnetic Generalized Polarizabilities